1. Field of the Invention
The present invention relates to a thin-film magnetic head and a method of manufacturing it, and more particularly to a thin-film magnetic head having a magnetic core of a two-film structure of which an upper and lower magnetic layers consist of two layers, respectively, and a method of fabricating it.
2. Description of the Related Art
These days, thin-film magnetic heads having a magnetic core of a two-film structure of which an upper and lower magnetic layers consist of two layers, respectively, have been proposed. In such thin-film magnetic heads, the upper and lower magnetic layers at the magnetic gap region facing a recording medium are thin comprising a single layer, respectively, while the upper and lower magnetic layers at a distance from the magnetic gap region are thick comprising two layers, respectively. Such structure improves the magnetic flux density at the magnetic gap region, prevents magnetization saturation for recording data onto the recording medium, enhances the resolution of the magnetic head for reproduction and also the efficiency of electromagnetic conversion.
FIG. 1 is a sectional view showing one example of the thin-film magnetic head of said two-film structure, the magnetic head being shown as split into two sections for electromagnetic conversion and wiring, respectively, indicated with H1 and H2, respectively. The wiring section H2 provides a connection between input/output terminal 15a and the center D of coil 8. The electromagnetic conversion section H1 shown in FIG. 1 is composed of a substrate 1 having formed thereon an under-film 2 on which a lower first magnetic film 4 and a lower second magnetic film 5, forming together a lower magnetic layer 3, are formed. Further, a magnetic gap film 6 is formed on the lower second magnetic film 5. This magnetic gap film 6 is partially open at a region B away from the head portion A facing the magnetic recording medium to provide a connection between a portion of the lower magnetic layer 3 and a portion of an upper magnetic layer 10. Furthermore, there is formed on the magnetic gap film 6 an insulating layer 7 in which a coil 8 is formed. Besides, there is formed on the insulating layer 7 an upper first magnetic film 11 and an upper second magnetic film 13 which form together the upper magnetic layer 10.
At the electromagnetic conversion section H1 shown in FIG. 1, the upper first magnetic film 11 and the lower second magnetic film 5 are in contact with each other through the open region B in the magnetic gap film 6, so that the upper magnetic layer 10 and lower magnetic layer 3 are magnetically coupled to each other. The upper magnetic layer 10 is cut off at the region C as shown, so that the upper magnetic layer 10 and lower magnetic layer 3 form together a magnetic core.
As shown at the wiring section H2 in FIG. 1, a first wiring 8a is formed on the magnetic gap film 6a. This magnetic gap film 6a is made of a same material as the magnetic gap film 6 at the electromagnetic conversion section H1 and formed simultaneously with the magnetic gap film 6. The first wiring 8a is made of a same material as the coil 8 and formed simultaneously with the latter. There is formed, as a laminate on the first wiring 8a, an upper first magnetic film 11a and an upper second magnetic film 13a, which are made of the same materials as the upper first magnetic films 11 and upper second magnetic films 13 at the electromagnetic conversion section respectively and are formed simultaneously.
As shown at the electromagnetic conversion section H1 in FIG. 1, the upper first magnetic film 11a is connected to the center D of the coil 8, and the upper first magnetic film 11a and upper second magnetic film 13a form together a second wiring.
As shown at the wiring section H2 in FIG. 1, there is formed as laminated directly on the upper second magnetic film 13a an input/output terminal backing 14a on which an input/output terminal 15a is formed.
In the above-mentioned arrangement, the input/output terminal 15a and the center D of the coil 8 are connected to each other by means of the first wiring 8a, upper first magnetic film 11a and upper second magnetic film 13a (second wiring).
FIG. 2 is a schematic diagram showing the connection between the coil 8 and the input/output terminals 15a and 15b of the thin-film magnetic head shown in FIG. 1. As seen in FIG. 2, the input/output terminal 15a is intended to provide a connection with the center D of the coil 8. The input/output terminal 15b is intended for providing a connection with an outer circumference of the coil 8. As seen from FIGS. 1 and 2, the input/output terminal 15a and the center D of the coil 8 are connected to each other by means of the first wiring 8a and the second wiring formed by the upper first magnetic film 11a and upper second magnetic film 13a. Also, the outer circumference of the coil 8 and the input/output terminal 15b are connected to each other by means of the first wiring 8b and the second wiring formed by the upper first magnetic film 11b and upper second magnetic film 13b.
It should be noted that the above-mentioned first wiring 8b, upper first magnetic film 11b and upper second magnetic film 13b are not shown in FIG. 1. However, the first wiring 8b is made of a same material as the first wiring 8a shown in FIG. 1 and formed simultaneously with the latter. Also the upper first and second magnetic films 11b and 13b are made of same materials as the upper first and second magnetic films 11a and 13a, respectively, shown in FIG. 1 and formed simultaneously with the latter. In FIG. 2, the reference numeral 14b indicates an input/output terminal backing for the input/output terminal 15b.
Also, an invention of an improvement of the thin-film magnetic head shown in FIG. 1 is disclosed in the Japanese Unexamined Patent Publication (Kokai) No. 59-194717 and U.S. Pat. No. 4,550,353. FIG. 3 is a schematic diagram showing that improved thin-film magnetic magnetic head. As shown at the electromagnetic conversion section H1' in FIG. 3, a substrate 1' has formed thereon an under-film 2' on which are formed lower first and second magnetic films 4' and 5' forming together a lower magnetic layer 3'. Further, a magnetic gap film 6' is formed on the lower second magnetic film 5'. The magnetic gap film 6' is partially opened at the region B' away from the region A' facing the magnetic recording medium to provide a connection between a portion of the lower magnetic layer 3' and a portion of the upper magnetic layer 10'. Furthermore, the magnetic gap film 6' has formed thereon an insulating layer 7' in which a coil 8' is provided. In addition, the insulating layer 7' has formed thereon as laminated an upper first magnetic film 11', inorganic insulating film 12' and an upper second magnetic film 13', which form together an upper magnetic layer 10'.
As shown at the electromagnetic conversion section H1' in FIG. 3, the first upper magnetic film 11' and lower second magnetic film 5' are in contact with each other through the open region B' in the magnetic gap film 6' so that the upper magnetic layer 10' and lower magnetic layer 3' are magnetically coupled to each other. Further, the upper magnetic layer 10' is cut off at the region C' as shown, so that the upper magnetic layer 10' and lower magnetic layer 3' form together a magnetic core.
As shown at the wiring section H2' in FIG. 3, the magnetic gap film 6a' has formed thereon a first wiring 8a'. The magnetic gap film 6a' is made of a same material as the magnetic gap film 6' and formed simultaneously with the latter. The first wiring 8a' has formed as laminated thereon an upper first magnetic film 11a', inorganic insulating film 12a' and an upper second magnetic film 13a'. The upper first magnetic film 11a' is made of a same material as the upper first magnetic film 11 shown at the electromagnetic conversion section H1' and formed simultaneously with the latter. Also the inorganic insulating film 12' is made of a same material as the inorganic insulating film 12' shown at the wiring section H2' and formed simultaneously with the latter.
The thin-film magnetic head shown in FIG. 3 differs from that shown in FIG. 1 in that there are provided the inorganic insulating film 12' between the upper first magnetic film 11' and upper second magnetic film 13' and the inorganic insulating film 12a' between the upper first magnetic film 11a' and upper second magnetic film 13a'. The inorganic insulating films 12' and 12a' of which the etching speeds are low are provided for the following reasons. Namely, the existence of the inorganic insulating film 12' permits to prevent any over-etching of the upper first magnetic film 13' at the region A' facing the magnetic recording medium applied on the thin-film magnetic head. As a result, the upper first magnetic film 13, at the region A' facing the magnetic recording medium applied to the thin-film magnetic head is so formed as to have a predetermined thickness. Further, a thin-film magnetic head is formed having the upper magnetic layer 10' which is thick at the position away from the region A' facing the magnetic recording medium.
On the other hand, the provision of the inorganic insulating film 12a' between the upper first and second magnetic films 11a' and 13a' will cause the following problems: that is, as shown at the electromagnetic conversion section H1' in FIG. 3, the upper first magnetic film 11a' is connected to the center D' of the coil 8'. Therefore, the upper first magnetic film 11a' forms a second wiring. In the conventional method of fabricating thin-film magnetic head, however, the input/output terminal backing 14a' is laminated directly on the upper second magnetic film 13a' and the input/output terminal 15a' is formed on the input/output terminal backing 14a' as shown at the wiring section H2' in FIG. 3. As a result, the input/output terminal 15a' (input/output terminal backing 14a' ) and the center D' of the coil 8' cannot have an electrical continuity between them due, to the existence of the inorganic insulating film 12a' regardless of the existence of the upper first magnetic film 11a' (second wiring).
The above-mentioned problem of the connection between the coil 8' and input/output terminal 15a' will occur similarly in the connection between the outer circumference of the coil 8' and input/output terminal (corresponding to the input/output terminal 15b in FIG. 2).